Russian orbital launch vehicle. The Kvant was the Soviet third generation light launch vehicle planned to replace the Kosmos and Tsyklon series. Unlike the vehicles it was to replace, the booster used non-toxic 'environmentally friendly' liquid oxygen/kerosene propellants. Although such a light launch vehicle was on Space Forces wish lists since 1972, full scale development was again deferred due to the crash effort on Soviet 'star wars' in the second half of the 1980's. RKK Energia marketed the vehicle design from 1994 to 2001, but could find no source for development funds.

The vehicle would have used two modified Zenit-2 second stage RD-0120 engines in the first stage with a total liftoff thrust of 291 metric tons. The second stage was the Block DM as developed for the Zenit-3. Payload to a low earth orbit would have been 5.2 metric tons from Baikonur, 4.5 metric tons from Plesetsk, and 5.8 metric tons from an equatorial Sea Launch platform. The Block DM could have put a 700 kg payload into geosynchronous orbit from Sea Launch.

A later version of Kvant, proposed by RKK Energia in 2001, used four 'RD-120.21' adaptations of the RD-120 engine, together with two 11D121 verniers. The second stage was the DM-SL stage developed for the Sea Launch Zenit-3SL. The proposed control system was the PV-300 high-frequency 3-axes gyrostabilized platform and Biser-3 digital computer. The payload fairing would be that used with the Block DM upper stage on the Proton 8K82K. In this configuration the vehicle had an increased launch mass of 275 metric tons but essentially the same payload-to-orbit performance of the earlier design.